Full-laminating OCA optical adhesive capable of filling blind hole section difference and preparation method thereof

Abstract

The application relates to the technical field of adhesives, and discloses a full-laminating OCA optical adhesive capable of filling a blind hole section difference and a preparation method thereof, raw materials of the optical adhesive include 100 parts by weight of an acrylate monomer, 15-40 parts of a crosslinking agent and the like; the crosslinking agent is 1,6-hexanediol diacrylate, polyethylene glycol di(N-acryl-L-arginine ester) or the like. The polyethylene glycol di(N-acryl-L-arginine ester) has the function of a diluent, can improve the fluidity of the adhesive, and promotes the flow and filling of the adhesive. The OCA adhesive has very high tensile properties and bonding properties. The plasticity is excellent, the blind hole section difference space can be completely filled, the viscosity is sufficient, the cover plate and the module can be stably bonded. Through secondary curing, the shape of the OCA is fixed, the elasticity and flexibility are increased, impact energy can be stably absorbed, and damage caused by stress concentration can be avoided.

Description

Technical Field

[0001] This invention relates to the field of adhesive technology, specifically to a fully bonded OCA optical adhesive capable of filling blind hole steps and its preparation method. Background Technology

[0002] OCA optical adhesive possesses excellent optical and adhesive properties and is widely used in electronic devices such as smartphones, tablets, and touch displays. With consumers' increasing demand for high screen-to-body ratio devices, mobile phone manufacturers are gradually adopting full-screen designs, requiring components such as front-facing cameras and sensors to be hidden beneath the screen. To achieve this, the screen structure needs to reserve a light-transmitting area for the camera component without affecting the display effect. The camera is located directly below a blind hole below the backlight module, but there is a significant step difference at the blind hole. Commonly used acrylic-based OCA optical adhesives have poor flowability, and this step difference at the blind hole can easily cause problems such as insufficient OCA adhesive filling, air bubbles, and weak adhesion. Therefore, OCA adhesive is required to have high flowability, high filling capacity, and reduced stress concentration properties. Patent application CN115851178A discloses an acrylic pressure-sensitive adhesive for filling blind holes and its preparation method. The acrylic pressure-sensitive adhesive for filling blind holes prepared from raw materials such as acrylic monomer, azobisisobutyronitrile, and benzoyl peroxide has advantages such as high modulus, good filling effect, and no overflow after filling. However, this patent does not improve the elasticity and flexibility of the adhesive, and stress concentration is easily generated after filling blind holes, resulting in damage. Summary of the Invention

[0003] To address the shortcomings of existing technologies, this invention provides a fully adhesive OCA optical adhesive capable of filling blind hole steps and its preparation method, solving the problems of poor flowability, poor filling performance, and low bonding performance of acrylate OCA optical adhesives.

[0004] The technical solution of this invention is: a method for preparing a fully bonded OCA optical adhesive capable of filling blind hole steps. (1) Toluene, polyethylene glycol, N-acryloyl-L-arginine, catalyst, and polymerization inhibitor were added to a flask. The mixture was heated and stirred to carry out the esterification reaction. After filtration, the filtrate was distilled under reduced pressure. The product was added to a saturated sodium chloride solution and extracted with dichloromethane. After separation, the organic layer was distilled under reduced pressure and dried to obtain polyethylene glycol di(N-acryloyl-L-arginine ester). The reaction formula is as follows: .

[0005] (2) Add acrylate monomer, crosslinking agent, chain transfer agent and photoinitiator to the reactor, introduce nitrogen gas, stir and irradiate under high pressure mercury lamp to prepolymerize and obtain acrylate prepolymer; then add photoinitiator and crosslinking agent, stir and mix, degas, coat and pre-cur to obtain fully bonded OCA optical adhesive that can fill blind hole step differences.

[0006] Preferably, the reaction temperature in (1) is 105-110℃ and the reaction time is 12-18h.

[0007] Preferably, the molar ratio of polyethylene glycol, N-acryloyl-L-arginine, catalyst and polymerization inhibitor in (1) is 1:(2.6-3):(0.2-0.26):(0.02-0.03).

[0008] Preferably, the molecular weight of polyethylene glycol in (1) is 600-1000.

[0009] Preferably, the catalyst in (1) is p-toluenesulfonic acid.

[0010] Preferably, the polymerization inhibitor in (1) is hydroquinone.

[0011] Preferably, in (2), the temperature is controlled at 60-65℃ and the prepolymerization time is 2-3 min during the irradiation for prepolymerization.

[0012] Preferably, in (2), the pre-curing is carried out by irradiation under a high-pressure mercury lamp for 1-2 minutes.

[0013] Preferably, in (2), the amount of acrylate monomer is 100 parts by weight, the amount of crosslinking agent is 15-40 parts, the amount of photoinitiator is 0.2-0.5 parts by weight, and the amount of chain transfer agent is 0.01-0.04 parts by weight.

[0014] Preferably, the crosslinking agent in (2) includes 1,6-hexanediol diacrylate, tripropylene glycol diacrylate, dipropylene glycol diacrylate, and polyethylene glycol di(N-acryloyl-L-arginine ester).

[0015] Preferably, in (2), the acrylate monomers include methyl acrylate, ethyl acrylate, butyl acrylate, isooctyl acrylate, methyl methacrylate, isobornyl acrylate, hydroxypropyl acrylate, and hydroxyethyl acrylate.

[0016] Preferably, the photoinitiator in (2) includes one or more of phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, ethyl 2,4,6-trimethylbenzoylphosphonate, 1-hydroxy-cyclohexyl-phenyl ketone, and 2-hydroxy-methylphenylpropane-1-one.

[0017] Preferably, (2) the medium chain transfer agent includes dodecyl mercaptan.

[0018] The beneficial technical effects of this invention are as follows: By mixing acrylate prepolymer, polyethylene glycol di(N-acryloyl-L-arginine ester), photoinitiator, etc., and pre-curing, a fully bonded OCA optical adhesive that can fill blind hole gaps is obtained. Polyethylene glycol di(N-acryloyl-L-arginine ester) contains alkenyl groups, which can act as a crosslinking agent and undergo a crosslinking and curing reaction with the prepolymer. At the same time, polyethylene glycol di(N-acryloyl-L-arginine ester) contains multiple ester groups, which have good compatibility with the acrylate polymer matrix and can be uniformly dispersed in the OCA adhesive matrix, acting as a diluent and improving the fluidity of the OCA adhesive. It has a large creep value and high plasticity and filling properties, which can meet the requirements for filling lens module gaps and promote the flow of adhesive to fill the tiny blind holes in the mobile phone camera.

[0019] The polyethylene glycol di(N-acryloyl-L-arginine ester) of this invention contains a large number of polar groups such as amide bonds and amino groups, which can improve the adhesion between the adhesive and the adherend, enabling the OCA adhesive to maintain its fluidity while possessing high tensile shear strength and bonding performance. Furthermore, the amide bonds and amino groups form hydrogen bonds in the acrylate polymer, increasing the intermolecular forces and creating cross-linking entanglement between the molecular chains. This enhances the elasticity and flexibility of the polymer matrix, significantly increasing the elongation at break. It can completely fill the blind hole step spaces, absorb stress, promote stress buffering, and prevent stress concentration and damage. Detailed Implementation

[0020] The specific embodiments of the present invention will be described in detail below. However, it should be noted that the scope of protection of the present invention is not limited to these specific embodiments, and all technical and scientific terms used in this specification have the meanings conventionally understood by those skilled in the art. In case of conflict, the definitions in this specification shall prevail.

[0021] Add 1 L of distilled water, 174 g of L-arginine, and 150 g of potassium carbonate to a flask. After stirring, purge with nitrogen gas and add 300 mL of diethyl ether. In an ice-water bath, add a solution of 300 mL of diethyl ether containing 90 mL of acryloyl chloride dropwise over a period of 45 min. Stir the reaction for 3 h, allow it to stand, and then pour off the upper oil phase. Add 2 mol / L sodium hydroxide solution to the aqueous phase to adjust the pH to 7.4, then extract with diethyl ether. Freeze-dry the aqueous phase, add the product to 2 L of methanol, stir, filter, and distill under reduced pressure to obtain N-acryloyl-L-arginine with the structural formula [insert structural formula here]. .

[0022] Example 1: (1) Add 500 mL of toluene, 0.2 mol of polyethylene glycol 600, 0.56 mol of N-acryloyl-L-arginine, 52 mmol of p-toluenesulfonic acid, and 4 mmol of hydroquinone to a flask equipped with a water separator and a reflux tube. Heat to 110 °C and stir for esterification reaction for 12 h. Filter, distill the filtrate under reduced pressure, add the product to a saturated sodium chloride solution, extract with dichloromethane, separate, distill the organic layer under reduced pressure, and dry to obtain liquid polyethylene glycol di(N-acryloyl-L-arginine ester).

[0023] (2) Add 570g butyl acrylate, 120g isooctyl acrylate, 270g methyl methacrylate, 40g hydroxyethyl acrylate, 8g tripropylene glycol diacrylate, 0.17g dodecanethiol, and 0.5g phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide to the reactor, introduce nitrogen gas, stir, and then irradiate under a high-pressure mercury lamp at a controlled temperature of 65℃ for 2.5 min to obtain acrylate prepolymer; then add 3.2g phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide and 142g polyethylene glycol di(N-acryloyl-L-arginine ester), stir and mix, degas, coat, and irradiate under a high-pressure mercury lamp for 1 min to obtain fully bonded OCA optical adhesive that can fill blind hole steps.

[0024] Example 2: (1) Add 600 mL of toluene, 0.2 mol of polyethylene glycol 800, 0.6 mol of N-acryloyl-L-arginine, 40 mmol of p-toluenesulfonic acid, and 5 mmol of hydroquinone to a flask equipped with a water separator and a reflux tube. Heat to 105 °C and stir for esterification reaction for 18 h. Filter, distill the filtrate under reduced pressure, add the product to a saturated sodium chloride solution, extract with dichloromethane, separate, distill the organic layer under reduced pressure, and dry to obtain liquid polyethylene glycol di(N-acryloyl-L-arginine ester).

[0025] (2) Add 510g butyl acrylate, 140g isooctyl acrylate, 320g methyl methacrylate, 30g hydroxyethyl acrylate, 6g 1,6-hexanediol diacrylate, 0.22g dodecanethiol, and 0.4g 2-hydroxy-methylphenylpropane-1-one to the reactor, introduce nitrogen gas, stir, and then irradiate under a high-pressure mercury lamp at a controlled temperature of 60℃ for 3 minutes to obtain acrylate prepolymer; then add 1.9g 2-hydroxy-methylphenylpropane-1-one and 194g polyethylene glycol di(N-acryloyl-L-arginine ester), stir and mix, degas, coat, and irradiate under a high-pressure mercury lamp for 2 minutes to obtain fully bonded OCA optical adhesive that can fill blind hole steps.

[0026] Example 3: (1) Add 600 mL of toluene, 0.2 mol of polyethylene glycol 600, 0.52 mol of N-acryloyl-L-arginine, 48 mmol of p-toluenesulfonic acid, and 4 mmol of hydroquinone to a flask equipped with a water separator and a reflux tube. Heat to 110 °C and stir for esterification reaction for 12 h. Filter, distill the filtrate under reduced pressure, add the product to a saturated sodium chloride solution, extract with dichloromethane, separate, distill the organic layer under reduced pressure, and dry to obtain liquid polyethylene glycol di(N-acryloyl-L-arginine ester).

[0027] (2) Add 500g butyl acrylate, 140g isooctyl acrylate, 310g methyl methacrylate, 50g hydroxyethyl acrylate, 5g dipropylene glycol diacrylate, 0.15g dodecanethiol, and 0.5g 2-hydroxy-methylphenylpropane-1-one to the reactor, introduce nitrogen gas, stir, and then irradiate under a high-pressure mercury lamp at a controlled temperature of 65℃ for 2 minutes to obtain acrylate prepolymer; then add 2.2g 2-hydroxy-methylphenylpropane-1-one and 295g polyethylene glycol di(N-acryloyl-L-arginine ester), stir and mix, degas, coat, and irradiate under a high-pressure mercury lamp for 1 minute to obtain fully bonded OCA optical adhesive that can fill blind hole steps.

[0028] Example 4: (1) Add 600 mL of toluene, 0.2 mol of polyethylene glycol 600, 0.6 mol of N-acryloyl-L-arginine, 42 mmol of p-toluenesulfonic acid, and 6 mmol of hydroquinone to a flask equipped with a water separator and a reflux tube. Heat to 105 °C and stir for esterification reaction for 18 h. Filter, distill the filtrate under reduced pressure, add the product to a saturated sodium chloride solution, extract with dichloromethane, separate, distill the organic layer under reduced pressure, and dry to obtain liquid polyethylene glycol di(N-acryloyl-L-arginine ester).

[0029] (2) Add 520g butyl acrylate, 110g isooctyl acrylate, 340g methyl methacrylate, 30g hydroxyethyl acrylate, 6g 1,6-hexanediol diacrylate, 0.22g dodecyl mercaptan, and 0.7g phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide to the reactor, introduce nitrogen gas, stir, and irradiate under a high-pressure mercury lamp at a controlled temperature of 60℃ for 3 minutes to obtain acrylate prepolymer; then add 2.8g phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide and 394g polyethylene glycol di(N-acryloyl-L-arginine ester), stir and mix, degas, coat, and irradiate under a high-pressure mercury lamp for 1 minute to obtain fully bonded OCA optical adhesive that can fill blind hole steps.

[0030] Comparative Example 1 differs from Example 1 in that it does not contain polyethylene glycol di(N-acryloyl-L-arginine ester).

[0031] (1) Add 570g butyl acrylate, 120g isooctyl acrylate, 270g methyl methacrylate, 40g hydroxyethyl acrylate, 8g tripropylene glycol diacrylate, 0.17g dodecanethiol, and 0.5g phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide to the reactor, introduce nitrogen gas, stir, and then irradiate under a high-pressure mercury lamp at a controlled temperature of 65℃ for 2.5 min to obtain acrylate prepolymer; then add 3.2g phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, stir and mix, degas, coat, and irradiate under a high-pressure mercury lamp for 1 min to obtain OCA optical adhesive.

[0032] Comparative Example 2 differs from Example 1 in that it uses polyethylene glycol diacrylate 1000 (molecular weight approximately 1000) instead of polyethylene glycol di(N-acryloyl-L-arginine ester).

[0033] (1) Add 570g butyl acrylate, 120g isooctyl acrylate, 270g methyl methacrylate, 40g hydroxyethyl acrylate, 8g tripropylene glycol diacrylate, 0.17g dodecanethiol, and 0.5g phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide to the reactor, introduce nitrogen gas, stir, and then irradiate under a high-pressure mercury lamp at a controlled temperature of 65℃ for 2.5 min to obtain acrylate prepolymer; then add 3.2g phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide and 142g polyethylene glycol diacrylate 1000, stir and mix, degas, coat, and irradiate under a high-pressure mercury lamp for 1 min to obtain OCA optical adhesive.

[0034] Comparative Example 3 differs from Example 1 in that it uses acryloyl polyetheramine instead of polyethylene glycol di(N-acryloyl-L-arginine ester).

[0035] (1) Add dichloromethane, 200g polyetheramine D400 and 101g triethylamine to a flask, purge with nitrogen, add 135g acryloyl chloride dropwise in an ice-water bath, stir and react at 20°C for 8h, filter, add saturated sodium chloride solution to the filtrate, shake to extract, separate, distill under reduced pressure and dry to obtain acryloyl polyetheramine.

[0036] (2) Add 570g butyl acrylate, 120g isooctyl acrylate, 270g methyl methacrylate, 40g hydroxyethyl acrylate, 8g tripropylene glycol diacrylate, 0.17g dodecanethiol, and 0.5g phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide to the reactor, introduce nitrogen gas, stir, and then irradiate under a high-pressure mercury lamp at a controlled temperature of 65℃ for 2.5 min to obtain acrylate prepolymer; then add 3.2g phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide and 142g acryloyl polyetheramine, stir and mix, degas, coat, and irradiate under a high-pressure mercury lamp for 1 min to obtain OCA optical adhesive.

[0037] The OCA optical adhesive was irradiated under a UV lamp for 2 minutes, and its creep properties were tested using a rheometer.

[0038] OCA optical adhesive was bonded between the glass sheet and the PCB board module. After being irradiated with a UV lamp for 5 minutes, and then subjected to degassing at 45℃ and 4.5 kg for 30 minutes, the OCA underwent plastic deformation, flowed into the blind hole area, and filled the step difference. The tensile shear strength was tested according to GB / T 7124-2008 standard.

[0039] OCA optical film was prepared by irradiating it under a UV lamp for 2 minutes and its tensile properties were tested according to the method of standard GB / T 1040.1-2025.

[0040] The performance test results are shown in Table 1.

[0041] Table 1 Performance Tests

[0042] Tests showed that the acrylate OCA optical adhesive in Comparative Example 1 had a low creep value, poor flowability, which was not conducive to the flow of adhesive to fill blind holes. It also had low tensile shear strength, poor bonding performance, low elongation at break, and poor flexibility and elasticity.

[0043] In each embodiment, polyethylene glycol di(N-acryloyl-L-arginine ester) was added. Containing multiple ester groups, it exhibits good compatibility with the acrylate polymer matrix and can be uniformly dispersed in the OCA adhesive matrix. As a diluent, it improves flowability, has a high creep value, and possesses excellent plasticity and filling properties, promoting adhesive flow and filling blind pores. Furthermore, polyethylene glycol di(N-acryloyl-L-arginine ester) contains numerous amide bonds, amino groups, and other polar groups, which enhance the adhesion between the adhesive and the adherend, allowing the OCA adhesive to maintain flowability while possessing high tensile shear strength and bonding performance. Additionally, the amide bonds and amino groups form hydrogen bonds in the acrylate polymer, increasing intermolecular forces and creating cross-linking entanglement, thereby improving the elasticity and flexibility of the polymer matrix and significantly increasing the elongation at break.

[0044] Compared to Example 1, Comparative Example 2 incorporated conventional polyethylene glycol diacrylate, which does not contain a large number of amide bonds, amino groups, or other polar groups. Therefore, the tensile shear strength and elongation at break of the adhesive were lower than those of Example 1. Comparative Example 3 utilized the amidation reaction between the double-terminated amino groups of polyetheramine and acryloyl chloride. The resulting acryloyl polyetheramine did not contain ester groups, exhibited poor compatibility with acrylate polymers, poor dilution and viscosity reduction effects, low creep, and poor flowability. Consequently, the tensile shear strength and elongation at break of the adhesive were lower than those of Example 1.

[0045] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A full-lamination OCA optical adhesive capable of filling a blind hole section difference, characterized in that, The raw materials of the optical adhesive include 100 parts by weight of acrylate monomer, 15-40 parts by weight of crosslinking agent, 0.2-0.5 parts by weight of photoinitiator, and 0.01-0.04 parts by weight of chain transfer agent; The crosslinking agent is one or more of 1,6-hexanediol diacrylate, tripropylene glycol diacrylate, dipropylene glycol diacrylate, and polyethylene glycol di(N-acryloyl-L-arginine ester). 2.The full-matrix OCA optical adhesive with fillable blind hole step difference according to claim 1, characterized in that, The acrylate monomer is one or more of methyl acrylate, ethyl acrylate, butyl acrylate, isooctyl acrylate, methyl methacrylate, isobornyl acrylate, hydroxypropyl acrylate, and hydroxyethyl acrylate.

3. The method for preparing the fully bonded OCA optical adhesive capable of filling blind hole steps according to claim 1, characterized in that, The photoinitiator is one or more of phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, ethyl 2,4,6-trimethylbenzoylphosphonate, 1-hydroxy-cyclohexyl-phenyl ketone, and 2-hydroxy-methylphenylpropane-1-one.

4. The method for preparing the fully bonded OCA optical adhesive capable of filling blind hole steps according to claim 1, characterized in that, The chain transfer agent includes dodecyl mercaptan.

5. A method for preparing a fully bonded OCA optical adhesive capable of filling blind hole steps as described in any one of claims 1-4, characterized in that, The preparation method is as follows: (1) Add toluene, polyethylene glycol, N-acryloyl-L-arginine, catalyst and polymerization inhibitor to a flask, heat and stir to react, filter and distill the filtrate under reduced pressure, add the product to a saturated sodium chloride solution, extract with dichloromethane, separate and distill the organic layer under reduced pressure and dry to obtain polyethylene glycol di(N-acryloyl-L-arginine ester). (2) Add acrylate monomer, crosslinking agent, chain transfer agent and photoinitiator to the reactor, introduce nitrogen gas, stir and irradiate under high pressure mercury lamp to prepolymerize and obtain acrylate prepolymer; then add photoinitiator and crosslinking agent, stir and mix, degas, coat and precur to obtain fully bonded OCA optical adhesive that can fill blind hole step difference.

6. The method for preparing the fully bonded OCA optical adhesive capable of filling blind hole steps according to claim 5, characterized in that, The reaction temperature in (1) is 105-110℃ and the reaction time is 12-18h.

7. The method for preparing fully bonded OCA optical adhesive capable of filling blind hole steps according to claim 5, characterized in that, The molar ratio of polyethylene glycol, N-acryloyl-L-arginine, catalyst, and polymerization inhibitor in (1) is 1:(2.6-3):(0.2-0.26):(0.02-0.03).

8. The method for preparing the fully bonded OCA optical adhesive capable of filling blind hole steps according to claim 5, characterized in that, The molecular weight of the polyethylene glycol is 600-1000.

9. The method for preparing the fully bonded OCA optical adhesive capable of filling blind hole steps according to claim 5, characterized in that, The catalyst is p-toluenesulfonic acid, and the polymerization inhibitor is hydroquinone.

10. The method for preparing the fully bonded OCA optical adhesive capable of filling blind hole steps according to claim 5, characterized in that, In step (2), the temperature is controlled at 60-65℃ during prepolymerization and the prepolymerization time is 2-3 minutes. Precuring is performed by irradiation under a high-pressure mercury lamp for 1-2 minutes.

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